Laser metrology system

• Subject Area: Systems Engineering
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 559259153

Scientists at the Heinrich Heine University Düsseldorf intend to use the proposed system to perform precision measurements of rotational-vibrational transitions of stored, cold hydrogen molecular ions. All isotopologues - homonuclear (H2+, D2+, T2+) and heteronuclear (HD+, HT+, DT+) - are to be investigated. The measurements serve both to determine the nuclear radii and the masses of the simplest nuclei, and to search for or rule out additional forces between electrons and baryons or between baryons that could exist due to dark matter. The following new research directions will be pursued with the proposed laser metrology system: (1) increasing the accuracy of vibrational spectroscopy of HD+ and H2+ by several orders of magnitude into the 1E-15 range; (2) the first vibrational spectroscopy of D2+, T2+, HT+, DT+, with uncertainties of about 1E-14; (3) spectroscopy of H2+, the simplest molecule of all, in a Penning-Dehmelt trap, with an uncertainty of 1E-15. The investigations on H2+ also serve as a preliminary step for the precision spectroscopy of anti-H2+, consisting of a positron and two antiprotons. Such spectroscopy would enable a highly accurate test of CPT invariance. Anti-H2+ could become available at CERN in the near future, which is why preliminary investigations on the equivalent H2+ are indispensable. The proposed projects require a widely tunable, high-power, continuous-wave spectroscopy laser source that emits in the mid-infrared spectral range (2.5 - 3.9 micrometers) and is extremely narrow-band. Furthermore, the frequency of the light wave must be kept stable to 15 decimal places and it must also be possible to measure it. Therefore, a continuous-wave optical parametric oscillator is requested here, which is phase-stabilized to a frequency comb.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Lasermetrologiesystem
• Instrumentation Group: 5700 Festkörper-Laser
• Applicant Institution: Heinrich-Heine-Universität Düsseldorf
• Leader: Professor Stephan Schiller, Ph.D.